22%

Percent increased likelihood that babies who were exposed to antibiotics before 6 months of age became overweight by age 3, compared with unexposed infants, according to a new study by researchers at New York University. It’s not clear what underlies the link between early antibiotic use and later weight gain, but the researchers think it might have something to do with disturbances in the balance of healthy bacteria in the gut — some of which may be killed off by antibiotics — which influence how humans absorb calories and, therefore, their risk of obesity. Nearly a third of the 11,532 children in the study had received antibiotics by 6 months. [via International Journal of Obesity]